An Investigation of the Order-Disorder Transformation in the Nickel-29.1 Per Cent Molybdenum Alloy by Electrical Resistivity Measurements

This investigation is a continuation of research on the nickel-molybdenum binary alloy system which has been in progress in the Department of Chemical and Metallurgical Engineering of The University of Tennessee for the past several years in association with the Oak Ridge National Laboratory. The purpose of the present investigation was to develop an electrical resistivity method for studying the order-disorder transition in the nickel-molybdenum alloy of stoichiometric composition, Ni4Mo. The alloy containing 29.1 weight per cent molybdenum in nickel was prepared by melting 250-gram ingots in a direct arc furnace under an inert gas. These were homogenized in argon for 100 hours at 1200 degrees Celsius and water quenched to retain the high temperature face-centered-cubic alpha phase. Samples for electrical resistivity measurements were prepared by swaging (or rolling) and machining the homogenized ingots to approximately 0.1 inch diameter rods about 6 inches in length. Pretreatment of the alloy by quenching from above 868 degrees Celsius produced an initial state of retained alpha phase for subsequent resistivity measurements. Heat treatments below this temperature produced the long range order Ni4Mo phase. An apparatus was designed and constructed for the continuous measurement of electrical resistivity at high temperatures. This apparatus permitted the continuous recording of resistivity-temperature curves during heating and cooling through the transformation temperature of the alloy. It also provided a means to study the kinetics of ordering in the alloy using electrical resistivity as the index of order. The principal results of this investigation can be summarized as follows: 1. The resistivity-temperature curves for the alloy in the initially ordered state exhibited positive slopes but with a marked negative deviation from linearity which increased rapidly with increasing temperature. The alloy undergoes a discontinuous change in resistivity at the critical temperature (868 degrees C), characteristic of an order-disorder transformation. 2. From 868 degrees C to 1000 degrees C, the alpha phase exhibits a negative temperature coefficient of resistivity which has been attributed to a decreasing degree of short range order with increasing temperature. 3. When the alloy is cooled below the critical temperature a sharp decrease in resistivity occurs at undercoolings of 60-90 degrees C due to the rapid onset of ordering. The immediate degree of order, however, is not complete and the resistivity-temperature curve on further cooling is cooling-rate dependent. Holding at temperatures below the transformation temperature resulted in a slow decrease in resistivity as equilibrium was approached. 4. The temperature coefficient of resistivity of the retained alpha phase is negative near room temperature. However, at higher temperatures the resistivity increases rapidly to a maximum near 650 degrees C and then decreases. This behavior has been attributed to the existence of a critical domain size and/or degree of long range order developed on heating. 5. Isothermal transformation of the retained alpha phase to the low temperature beta phase at temperatures below the critical temperature was followed by measuring the change in resistivity which accompanies it. The most rapid transformation was found to occur at a temperatures in the range 760 degrees to 800 degrees C. 6. Isothermal resistivity-time curves were used to construct a time-temperature-transformation diagram for the alloy. The nose of the diagram was found to lie within the temperature range 710 degrees C to 775 degrees C. The rate of transformation was extremely slow below 600 degrees C

Comparative Analysis of World Market Projections with Special Regard to Wheat Prices

This paper presents a short comparative analysis of USDA and FAPRI projections for world wheat market prices until 2005. The relevance of different model assumptions regarding assumed inflation, exchange rates, policy parameters as well as shifts in demand and production development are discussed. A subsequent section focuses on the problem of a "world market price concept" for evaluating the potential of unsubsidized EU cereal exports. The Annex provides more detailed information on model assumptions and a comparison of other projected values, also including agricultural products other than wheat. Dieses Diskussionspapier stellt eine kurze vergleichende Analyse aktueller USDA- und FAPRI- Projektionen von Weltmarktpreisen fur Weizen bis 2005 vor. Die Relevanz verschiedener Modellannahmen hinsichtlich Inflation, Wechselkurs, Politikparameter und Bestimmungsgrossen von Angebot und Nachfrage werden diskutiert. Einige Uberlegungen zur Problematik eines "Weltmarktpreiskonzeptes" bei der Abschatzung des Potentials unsubventionierter EU Getreideexporte schliessen sich an. Der Anhang stellt detailliertere Informationen zu Modellannahmen sowie den Vergleich weiterer projezierter Kennzahlen bereit, die auch andere Agrarprodukte einschliessen.Demand and Price Analysis,

Vom integrativen Ansatz zum lernenden Konzept: Evaluation im Projekt "Schule interaktiv"

Im Projektfokus steht der Beitrag, den neue Medien zur Ausgestaltung einer so genannten neuen Lehr-Lernkultur leisten. Hierbei nehmen die Lernförderung und die Entwicklung von Medienkompetenz der Schüler/innen sowie die Stärkung medienpädagogischer Kompetenz der Lehrer/innen eine zentrale Rolle ein. Partner im Projekt «Schule interaktiv» sind vier weiterführende Schulen (eine Mittelschule, zwei Gymnasien und eine integrierte Gesamtschule) in den Bundesländern Sachsen, Hessen und Nordrhein-Westfalen, die Deutsche Telekom Stiftung und der Arbeitsbereich Bildung und Technik am Institut für Allgemeine Pädagogik und Berufspädagogik der TU Darmstadt. «Schule interaktiv» versteht sich als Schulentwicklungsprojekt und zielt auf eine Veränderung des Regelunterrichts in allen Fächern und Klassenstufen. Angesprochen ist die ganze Schule, die ausdrücklich Spielraum hat, ihren eigenen Weg zu beschreiten

The Heritage Leadership Process: Exploring Meaning Making and Social Emotional Competencies in Heritage Interpretation and Education for Sustainability

This study explores qualities identified as being critical to leadership work in heritage fields as identified by established leaders in heritage work. It also establishes a foundational definition of the term heritage leadership. After reviewing existing data to identify significant questions related to heritage leadership, the research team interviewed leaders in HIn and Education for Sustainability with a specific focus on leadership, meaning making, and social emotional competencies as guiding constructs in heritage leadership. A proposed definition of the term heritage leadership resulted: Heritage leaders aspire to serve others and to create meaningful connections to shared natural and cultural heritage through contextual application of skills and competencies, thereby fostering understanding with the intent to preserve and protect heritage for future generations. This study further explored heritage leadership as a process that leaders follow stemming from personal aspirations and attributes and moving to the development of skill sets and mindsets in preparation for engagement in meaning making as a desired outcome of heritage leadership activities. The characteristics identified in this heritage leadership process guide recommendations for organizational focus on personal and professional development opportunities for staff and students in the related fields. Generation of meaningful, emotional connections to shared social, cultural, and natural heritage is seen by heritage leaders as critical to engaging citizenry in efforts to understand, preserve, and protect shared heritage. Heritage leaders believe that the forging of these connections is crucial to the future well-being of our communities and societies at larg

Cleaning ability and induced dentin loss of a magnetostrictive ultrasonic instrument at different power settings

Some laboratory studies have evaluated the oscillation mode of ultrasonic scalers. None of them recorded its influence on calculus removal and quantified dental hard tissue loss. This study aimed to compare the performance of a magnetostrictive ultrasonic instrument at different power settings in vitro in relation to the tip oscillation activity. The oscillation activity of the straight Slimline® insert in the Cavitron® ultrasonic scaling device was analyzed at five different power settings with the help of two laser vibrometers. The performance of this instrument was tested on 60 roots of human single-rooted teeth. Twelve roots each were randomly assigned to be instrumented at a given power setting. Every root was instrumented for 120s at a standardized instrumentation force of 0.1 ± 0.05N. In addition, another 30 periodontally involved roots with subgingival calculus were instrumented accordingly to assess the calculus removal potential. The surface characteristics after instrumentation were analyzed under scanning electron microscope. The instrumentation at minimum power setting resulted in an mean increase of the root surface roughness of 0.18 ± 0.28 compared to 0.51 ± 0.48 at maximum power setting (P = 0.0327). The loss of dental hard tissue amounted to 11.37 ± 3.64 at minimum compared to 23.37 ± 15.76 at maximum power (P = 0.0010). The higher the power setting, the more calculus was removed. The values of the latter ranged between 4.04 ± 1.87 and 11.26 ± 4.66mm2 of cleaned dentin surface area (P = 0.0065). At lower power settings, a more favorable relation between cleaning ability, loss of dentine, and surface roughness was foun

Did domestic violence really increase in the early phase of the COVID-19 pandemic?:Results of an interview-based observational study

Objectives: The COVID-19 lockdown may lead to rising numbers of domestic violence (DV), especially among previously victimized individuals. The aim of this study was to investigate the development and influential factors of DV during the early COVID-19 lockdown. Methods: In this telephone-based study, previous participants with (n = 34) and without (n = 33) DV completed questionnaires on DV, attachment and COVID-19 related stressors. Development of DV and influential factors were investigated with repeated measures ANOVAs and linear regression models. Results: Individuals with prior DV reported significantly higher DV than previously not affected individuals. However, a statistically significant decrease of DV was found in the group with prior DV. Past DV, childlessness and insecure attachment, but not COVID-19 related stressors predicted current DV. Conclusions: In light of an insecure attachment style lockdown measures may have led to a temporary relationship stabilization. However, a reassessment is necessary to evaluate whether this stabilization was a short-time trend only

Career Goals and Student Perceptions of a Post-Professional Occupational Therapy Doctoral Experiential Component

Clinical doctoral education for occupational therapy includes the acquisition of advanced clinical reasoning skills, leadership capacity, and opportunities for professional development and career achievement. Post-professional students represent motivated individuals seeking to enhance their education, experiences, and explore professional growth opportunities. While not required, the final semester of a clinical doctoral program typically includes a doctoral experiential component (DEC), or culminating project. The purpose of this retrospective, mixed-methods study was to examine the DEC goals and experiences of post-professional occupational therapy doctoral (POTD) students. A total of 49 student DEC proposals, each including multiple personal goals, were categorized according to one or more POTD program goals. The most frequently selected long-term DEC goals by participants in this study were developing educative roles (n = 37, 27.30%), scholarly activities (n = 31, 22.96%), and advanced clinical skills (n = 31, 22.96). The DEC goals developed by the students were also categorized according to the experience as perceived by the students. Three primary areas of growth experienced by the students during their DEC were: (1) improved self-awareness and confidence through reflection, (2) a challenging, yet fulfilling, experience and (3) translation of new knowledge and skills to practice. The outcomes of this study may offer insight for administrators and prospective students of post-professional programs and align with the American Occupational Therapy Association’s Vision 2025 to produce effective and collaborative leaders capable of implementing evidence-based, client-centered, and cost-effective treatment to influence the complexities of healthcare